The following statement about influences is most accurate: they can be internal and external. Internal influences depend on the person her/hisself and include motivation, personality, attitude, lifestyle... External influences on the other hand come from the environment . Examples include: economic and political environment, technological changes, social changes,...
If you aren't checking yourself then you may have a problem. For example you could have testicular cancer and you wouldn't know without feeling an unusual bump in that area.
